Rotary engines having two intermeshing rotors, each having a plurality of lobes defining a plurality of voids there-between are known in the art. Such an engine is shown in the French patent to Costa, No. 544,127. An alternate configuration of rotors is shown in U.S. Pat. No. 3,435,808 to Allender. In both of these patents, air is compressed in a chamber formed by a lobe from one rotor and a void from the other rotor and is combusted either in the same chamber or a second chamber formed by the same rotor lobe and void. Configurations of this type suffer from a number of drawbacks. Of primary concern is the loss of power which inheres in the fact that the same rotor and void form the compression chamber and the power chamber. As a result, the power chamber is already expanding while compression is still taking place, thus shortening the effective power stroke significantly. In addition, since combustion takes place in a chamber formed by the rotor surfaces themselves, rotary engines of this type are subject to severe wear on the rotor surfaces. A further shortcoming of prior art rotary engines of this type is that they require many moving parts, and in particular, additional valves and timing gears therefor.